#!/usr/bin/perl

use strict;
use warnings;

# create TLS certificates for qpsmtpd
use File::Temp qw/ tempfile tempdir /;
use Getopt::Long;
use Sys::Hostname;

my %opts = ();
my $hostname = hostname();
print "Using hostname: $hostname\n";
my %defaults = (
    C  => 'XY',
    ST => 'unknown',
    L  => 'unknown',
    O  => 'QSMTPD',
    OU => 'Server',
    CN => $hostname,
);

GetOptions(\%opts, 
    'C|Country:s',
    'ST|State:s',
    'L|Locality|City:s',
    'O|Organization:s',
    'OU|OrganizationalUnit|U:s',
    'CN|CommonName|N:s',
    'emailAddress|email|E:s',
    'help|H',
);

usage() if $opts{help};

# initialize defaults
foreach my $key ( keys %defaults ) {
    $opts{$key} = $defaults{$key} unless $opts{$key}
}
$opts{emailAddress} = 'postmaster@'.$opts{CN};

mkdir('ssl') unless -d 'ssl';

my $CA_key = 'ssl/qpsmtpd-ca.key';
my $CA_crt = 'ssl/qpsmtpd-ca.crt';
my $CA_serial = 'ssl/.cert.serial';

my $template;
my ($CA, $CAfilename) = tempfile( $template, DIR => "ssl", UNLINK => 1);

print ${CA} return_cfg('CA');
close ${CA};

system('openssl', 'genrsa', '-out', $CA_key, 2048) == 0 
    or die "Cannot create CA key: $?";

system('openssl', 'req', '-config', $CAfilename, '-new', '-x509',
	'-days', (365*6), '-key', $CA_key,
	'-out', $CA_crt) == 0
    or die "Cannot create CA cert: $?";

my $SERVER_key = 'ssl/qpsmtpd-server.key';
my $SERVER_csr = 'ssl/qpsmtpd-server.csr';
my $SERVER_crt = 'ssl/qpsmtpd-server.crt';

my ($SERVER, $SERVERfilename) = tempfile( $template, DIR => "ssl", UNLINK => 1);
print ${SERVER} return_cfg($opts{OU});
close ${SERVER};

system('openssl', 'genrsa', '-out', $SERVER_key, 1024) == 0 
    or die "Cannot create server key: $?";

system('openssl', 'req', '-config', $SERVERfilename, '-new', 
	'-key', $SERVER_key, '-out', $SERVER_csr) == 0
    or die "Cannot create server cert: $?";

my ($SIGN, $SIGNfilename) = tempfile( $template, DIR => "ssl", UNLINK => 1);
print ${SIGN} <<"EOT";
extensions = x509v3
[ x509v3 ]
subjectAltName   = email:copy
nsComment        = tls certificate
nsCertType       = server
EOT
close ${SIGN};

open my $SERIAL, '>', $CA_serial;
print ${SERIAL} "01\n";
close ${SERIAL};

system('openssl', 'x509', '-extfile', $SIGNfilename, '-days', (365*2),
	'-CAserial', $CA_serial, '-CA', $CA_crt,
	'-CAkey', $CA_key, '-in', $SERVER_csr,
	'-req', '-out', $SERVER_crt) == 0
    or die "Cannot sign cert: $?";

exit(0);
	
sub return_cfg {
    my $OU = shift;
    my $RANDOM = int(rand(1000)).'RAN'.int(rand(1000)).'DOM';
    my $cfg = <<"EOT";
[ req ]
default_bits           = 1024
default_keyfile        = keyfile.pem
distinguished_name     = req_distinguished_name
attributes             = req_attributes
prompt                 = no
output_password        = mypass

[ req_distinguished_name ]
C                      = $opts{C}
ST                     = $opts{ST}
L                      = $opts{L}
O                      = $opts{O}
OU                     = $OU
CN                     = $opts{CN}
emailAddress           = $opts{emailAddress}

[ req_attributes ]
challengePassword      = $RANDOM challenge password
EOT
    return $cfg;
}

sub usage {
    print STDERR <<"EOT";

 $0 will generate a TLS certificate "the quick way",
 i.e. without interaction.  You can change some defaults however.
    
 These options are recognized:             Default:

  --C       Country (two letters, e.g. DE) $defaults{C}
  --ST      State (spelled out)            $defaults{ST}
  --L       City                           $defaults{L}
  --O       Organization                   $defaults{O}
  --OU      Organizational Unit            $defaults{OU}
  --CN      Common name                    $defaults{CN}
  --email   Email address of postmaster    postmaster\@CN
  --help    Show usage

EOT
    exit(1);
}